It's not an issue to put that much power from a V6. Actually it's easier task than put it from an Inline 6. No to mention that Italian V6 goes all the way to 625 HP.Not to say Stellantis can’t be a trailblazer, but color me suspicious when Mercedes uses a great 3.0 I6 that’s turbocharged with an electric supercharger that doesn’t put out that much power.
Turbo lag or better said lack of torque down low is something else. Just look at GME T4 HO from Italian side of FCA which is not yet available in US but it will be with Grecale. Electric supercharger and max torque of 450 Nm at just 1500 rpm.
From what I know, actually it wasn't hard to find, FCA R&D in Modena had worked on 3.0 V6 with 4th gen ZF 8HP80 MHEV. Models in question were Giulia, Stelvio, next gen GranTurismo and GranCabrio...